HOMEWORK32016

<span class='text_page_counter'>(1)</span>HOMEWORK_3 Problem 1 (a) Explain why alumina-containing zeolites possess chemically active surfaces. (b) What information isotherm differ from the Langmuir isotherm? Problem 2 On the basis of your reading of the following articles, address the following question regarding the nature of coke formed during hydrotreating: (a) What are the mechanisms for coke formation in hydrotreating? (b) What are the precursors to coke formation? (c) What are the different kinds of coke formed during HDS; show examples of chemical reactions leading to their formation. (d) Which is more important in determining catalytic activity: the kinds or amount of coke? Problem 3 The synthesis of ethylene (C2H4) is one of the largest chemical processes in the world. (a) Find a reasonable mechanism for the conversion of ethane (CH3CH3) into ethylene and hydrogen. (b) What other products would you expect? (c) Use the steady-state approximation to derive an expression for the rate of the overall reaction. (d) Estimate the preexponentials and activation barriers for each of the reactions. (e) How could you catalyze the reaction? Pick one homogeneous catalyst and one heterogeneous catalyst and explain how they would work. (f) In industrial practice, people use water and a zeolite (a solid catalyst) as catalysts. The water dissociates on the zeolite to yield OH and H. The water also reacts with carbon deposited on the pores of the zeolite. Explain how the water/zeolite mixture would catalyze the reaction. -------------------------------------------------------------.

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